NAME

stdc_bit_floor — round down to the previous power of 2

SYNOPSIS

/* -lc */
#include <stdbit.h>

unsigned char
stdc_bit_floor_uc(unsigned char value);

unsigned short
stdc_bit_floor_us(unsigned short value);

unsigned int
stdc_bit_floor_ui(unsigned int value);

unsigned long
stdc_bit_floor_ul(unsigned long value);

unsigned long long
stdc_bit_floor_ull(unsigned long long value);

typeof(value)
stdc_bit_floor(value);

DESCRIPTION

The stdc_bit_floor_type() family of functions rounds value down to the previous power of 2, where value is of type unsigned char, unsigned short, unsigned int, unsigned long, or unsigned long long for type being uc, us, ui, ul, or ull respectively. The stdc_bit_floor(value) type-generic macro picks the appropriate stdc_bit_floor_type() function based on the type of value.

RETURN VALUES

Returns value round down to the previous power of 2. If value is equal to zero, zero is returned.

SEE ALSO

stdbit(3), stdc_bit_ceil(3)

STANDARDS

The stdc_bit_floor_type() family of functions and the stdc_bit_floor() type-generic macro conform to ISO/IEC 9899:2024 (“ISO C23”).

HISTORY

The stdc_bit_floor_type() family of functions and the stdc_bit_floor() type-generic macro were added in FreeBSD 15.1.

AUTHOR

Robert Clausecker <fuz@FreeBSD.org>